無病無痛,沒有任何交通或人為意外的話,人類是否會進入不死永生狀態呢?730Please respect copyright.PENANA9arqHz8gZ3
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答案是,不會。730Please respect copyright.PENANAh7ENmjq4Lg
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箇中的原因,就是在於染色體亦即是DNA的運作機制之上。730Please respect copyright.PENANAmLdPXFtc48
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(圖1)正常人體細胞分裂的時候,染色體的長度會越來越短。730Please respect copyright.PENANAheBOXJOtGS730Please respect copyright.PENANAW62RcVnfWK
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(圖2)染色體的頂端區域,我們稱之為Telomere。正常細胞分裂後,Telomere的長度便會越來越短,所以導致染色體的總長度亦會有所減少。730Please respect copyright.PENANAA60JCAdITg730Please respect copyright.PENANAaoaHbxNLQN
730Please respect copyright.PENANAbghzQseSHB
(圖3)而幹細胞進行分裂的時候,則會有著Telomerase的協助,導致Telomere的長度便並不會有所減少。730Please respect copyright.PENANASNhTEop9j0
然而,當幹細胞變成正常細胞後,Telomerase的功能便會消失。730Please respect copyright.PENANARqBCEoVb8L730Please respect copyright.PENANABxk7TEPpK4
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(圖4)當Telomere長度削減到一定程度的時候,細胞便會自行啟動機制滅亡,又或者陷入衰老(Senescence)狀態。730Please respect copyright.PENANAyjSLrlFHKV
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細胞滅亡或衰老的話,器官的功能便會衰退,最後亦會支撐不住,無法正常運作,促成死亡。730Please respect copyright.PENANAGfTjZX3EeD730Please respect copyright.PENANAQg2eBuK5BZ
730Please respect copyright.PENANAJ9U3O87LFI
你可能會問,現在科技如此倡明,那麼我們只要學習幹細胞的那一套方式,動用外力重啟Telomerase功能,那不就能踏入永生嗎?730Please respect copyright.PENANACyXFkEZjCK
730Please respect copyright.PENANAv8wURpnQfo
這個思路並沒有錯,只不過代價就是會增加患癌的風險。730Please respect copyright.PENANAWnAwiXjyab
730Please respect copyright.PENANAtyX1RDIRzi
事實上,不少癌細胞的特徵就是Telomere長度非常之短,但又有著一定水平的Telomerase功能穩定維持著Telomere的長度,逃避進入滅亡的命運。730Please respect copyright.PENANAnULS90u5Sq
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另一方面的想,如果細胞真的是踏入「永生」狀態的話,終有一天無可避免會累積各種的DNA變異,促成癌細胞的誕生。730Please respect copyright.PENANAjOQ7jOJzDD
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(圖5)既然Telomere對細胞的壽命有著重要影響的話,那麼一些較為長壽的物種是否擁有較長的Telomere呢?730Please respect copyright.PENANArGn12go1Kc
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科學家比較各物種的Telomere後(Ref1),發現海豚的起始Telomere長度比人類高出6倍以上,但壽命長度始終是人類佔優。730Please respect copyright.PENANA18oMxRQHEW730Please respect copyright.PENANATpHout2ekB
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反而,決定物種壽命長度的其中一種因素,則是Telomere衰減的速度;730Please respect copyright.PENANAsrlV3dwod3
Telomere衰減的速度只是一個參考性的指標,並非絕對。物種的大小、新陳代謝機制的不同等等均會對壽命長度有著影響。730Please respect copyright.PENANAmTQkBnQiii
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人類每年約會減少71單位Telomere的長度,最高壽命為120歲。730Please respect copyright.PENANAl2rVwVJ2ks
而老鼠每年會減少7000單位Telomere長度,最高壽命為5歲。730Please respect copyright.PENANAfS8llyNEZi
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人類:每年減少71;120歲730Please respect copyright.PENANAx7ezNgBAVd
大象:每年減少109;66歲730Please respect copyright.PENANA65CpvPKPIE
紅鸛:每年減少105;60歲730Please respect copyright.PENANAycuoJHdj3L
海豚:每年減少766;52歲730Please respect copyright.PENANAXiTARSZhsp
兀鷲:每年減少209;41歲730Please respect copyright.PENANAgfQElPGuyr
海鷗:每年減少771;25歲730Please respect copyright.PENANAbxhWaKKEzp
馴鹿:每年減少531;22歲730Please respect copyright.PENANAo20AasnWOb
山羊:每年減少363;21歲730Please respect copyright.PENANAifwxAbQHQp
老鼠:每年減少7000;5歲730Please respect copyright.PENANAmJKYegiHan
730Please respect copyright.PENANA0G07BBH5tZ
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龜又是每年減少幾多呢?有待有心人發掘。730Please respect copyright.PENANATB6XRAJbhO
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如果想我快啲出文的話,請入去Penana網站科普專欄–薯不揀單俾一個like以及Bookmark,這對我非常之重要。730Please respect copyright.PENANAZm6KMNQDJb
730Please respect copyright.PENANA1URszNQREy
Link: https://www.penana.com/story/66244/%E7%A7%91%E6%99%AE%E5%B0%88%E6%AC%84-%E8%96%AF%E4%B8%8D%E6%8F%80%E5%96%AE/toc730Please respect copyright.PENANA2gU4tZOJBr
730Please respect copyright.PENANAztdfozytQk
同時亦可以在Penana網站裡按「買一嚿/半嚿薯仔」,以課金的方式推動我繼續搜羅資料寫文,多謝。730Please respect copyright.PENANAaNbNGU3p5N
730Please respect copyright.PENANAtxKlajghFq
Link:730Please respect copyright.PENANAry5XxH2cbs
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio730Please respect copyright.PENANAnliOl7UCcH
730Please respect copyright.PENANAydpHVV2ATR
730Please respect copyright.PENANA5M3QGfViQr
有興趣接收科學資訊的話,歡迎follow IG: potatopigtongue。730Please respect copyright.PENANAqSLK2VgRGv
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730Please respect copyright.PENANASNSYas1w69
Ref1:https://www.pnas.org/content/116/30/15122730Please respect copyright.PENANA24FHBjdaLR
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篇 #40
深入淺出–無病無痛的話,人類是否會永生?
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